This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Telomeres are the repeated segments found at the end of chromosomes, some of which are lost with each cell division, until a critical number is reached. This in turn, initiates cell senescence and the eventual death of the individual. In all vertebrates as well as in all mollusca studied to date, that sequence is TTAGGG. Longevity in Mollusca may be determined, in part, by the status of telomeres in the tissues. It has been shown that the bay scallop, Argopecten irradians, a local bivalve that lives less than two years, contains fewer telomeres than found in a close relative, Argopecten purpuratus, which can live 7-10 years. However, some species of marine animals, such as the lobster, Homarus americanus, do not have a defined life-span, rather they continue to grow until disease, predation or other environmental changes end their lives. This is due to the presence of telomerase in all of their tissues, enabling them to maintain a level of telomeres on the ends of their chromosomes, bypassing normal cell death. Animals with a defined life-span do not contain telomerase in their somatic tissues. The current study involves the determination of the presence or lack thereof, of the enzyme telomerase in all of the tissues of the Mahogany clam, Artica islandica, a bivalve found to live hundreds of years, with a recent example found that was over four hundred years old. An accurate method of determining the presence of this enzyme is employing real time PCR. One run was performed during the summer of 2008. I intend come back to do further work which would be sometime in the fall/winter season.